DS was/is big for his age but have found he has been between 15 - 16 kgs for a few months now. This is his first plateau too so just something to consider (he will be 3 in March) So we are looking at upgrading his seat from his current forward facing seat but I still want the protection of the 5 point harness and don't like the idea of just a seat belt. In my research of the convertible booster/forward facing seats is that the in build 5 point harness can't be used beyond 18 kgs either but you can buy a converter that converts the seat belt into a 5 point harness so you still get that safety aspect. As for brands I am currently looking at the Infa Secure range and have found they have very good reviews.

HTH